ISSN:
1551-2916
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Near-stoichiometric mullite (3Al2O32SiO2) that contained small amounts of calcium and magnesium was exposed to pure dry hydrogen gas at elevated temperatures. Exposure temperatures were 1050° and 1250°C, and exposure times were up to 500 h. Preferential attack of the aluminosilicate glass that was present in the grain boundaries of the mullite occurred after 125 h at 1250°C. Hydrogen scrubbing of the silica from the glassy grain boundaries and the mullite grains yielded a porous alumina-rich surface. The room-temperature strength increased after short exposure times at 1250°C (up to 125 h) and then decreased by 53% after exposure for 500 h. At 1050°C, all exposure times (25-500 h) decreased the strength. The room-temperature strength of mullite decreased 22% after 500 h in hydrogen at 1050°C. We also observed a rapid 25% strength loss after short exposure times at 1050°C, which was attributed to the calcium/hydrogen-assisted crystallization of the glassy grain-boundary phase.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1151-2916.1998.tb02426.x
Permalink
